Subcortical brain regions have been shown to have direct projections to the marginal zone (lamina 1) and substantia gelatinosa (lamina 2). These projections presumably play a role in the modulation of nociceptive input, which is known to relay in these laminae. The current proposal is to study the extent and influence of newly discovered direction projections from the cerebral cortex to spinal cord laminae 1 and 2. These initial studies will use single axon recording and intraaxonal injection of HRP to label physiologically identified corticospinal axons and their spinal terminations for both light and EM analyses. The results will provide information on the function of direct projections from the cerebral cortex to the superficial dorsal horn.